Excellent Corrosion Resistance of Inconel 718
Inconel 718 is a precipitation-hardenable nickel-based superalloy with outstanding resistance to high-temperature corrosion, oxidation, fatigue, and stress corrosion cracking. It is especially suitable for demanding environments involving high strength and elevated temperatures, such as aerospace, turbine engines, and the nuclear industry.
What is Inconel 718?
Inconel 718 (UNS N07718) is a nickel-based alloy strengthened by niobium (Nb) and titanium (Ti) precipitation hardening. It belongs to the superalloy family and exhibits excellent weldability and mechanical properties across a wide temperature range (−253°C to 704°C). It is widely used in aerospace structures, gas turbines, and oil & gas equipment.
Inconel 718 Chemical Composition (Typical Range)
| Standard System | Equivalent Grade |
| UNS | N07718 |
| W.Nr. | 2.4668 |
| ASTM | B637 / B670 / B805 |
| DIN | NiCr19Fe19Nb5Mo3 |
| ISO / EN | NiCr19NbMo |
Inconel 718 Chemical Composition
| Element | Content (%) |
| Nickel (Ni) | 50.0 – 55.0 |
| Chromium | 17.0 – 21.0 |
| Iron (Fe) | Balance |
| Molybdenum | 2.8 – 3.3 |
| Nb + Ta | 4.75 – 5.5 |
| Titanium | 0.65 – 1.15 |
| Aluminum | 0.2 – 0.8 |
| Manganese | ≤ 0.35 |
| Silicon | ≤ 0.35 |
| Carbon | ≤ 0.08 |
| Sulfur | ≤ 0.015 |
Inconel 718 Mechanical Properties (Annealed, Room Temperature)
| Property | Typical Value |
| Tensile Strength | ≥ 965 MPa |
| Yield Strength (0.2%) | ≥ 758 MPa |
| Elongation | ≥ 12% |
| Brinell Hardness | 220–330 HB |
| Creep Rupture Strength | ≥ 689 MPa at 650°C (100 hours) |
Inconel 718 Physical Properties
| Property | Value |
| Density | 8.19 g/cm³ |
| Melting Point Range | 1260–1336 °C |
| Thermal Conductivity | ~11.4 W/m·K (RT) |
| Electrical Resistivity | ~1.25 μΩ·m |
| Specific Heat | ~0.435 J/g·K |
| Magnetic Properties | Non-magnetic (Austenitic) |
Applications of Inconel 718
- Compressor blades, turbine disks, and fasteners in jet engines
- Rocket propulsion and aerospace components
- High-temperature bolts and structural parts
- Downhole tools and valves in oil & gas drilling
- Nuclear reactor components, heat exchangers, and steam generators
- Stamping dies, heavy-duty springs, and flange bolts
Advantages of Inconel 718
- Excellent high-temperature strength and creep rupture resistance
- Good corrosion and oxidation resistance at elevated temperatures
- Good weldability with low risk of hot cracking
- Wide operating temperature: cryogenic to 704°C
- Strengthened by aging heat treatment (no solid solution strengthening required)
- Very good resistance to chloride stress corrosion cracking
Limitations of Inconel 718
- High material and machining cost
- Microstructural degradation possible during prolonged exposure above 700°C
- Strict heat treatment control required for optimal performance
- High cutting tool wear; requires specialized tooling and coolant for machining
FAQ About Inconel 718
Yes. It maintains strength and creep resistance up to ~650°C for long-term service.
Absolutely. Inconel 718 is widely used in aircraft engines, rocket propulsion, and high-temperature aerospace components.
718 is precipitation-hardened for high strength; 625 is solid-solution strengthened with superior corrosion resistance but lower strength.
Not particularly. Due to its hardness, machining requires high-speed tooling and cooling systems.
Summary
This article introduces Inconel 718, explains the alloy, and discusses its composition, properties, and applications. For more information about Inconel 718, please get in touch with an MT.BOLTS representative.
MT.BOLTS offers fastener manufacturing and other value-added services to meet all your prototyping and production needs. Visit our website to learn more or request a quote.
